The process cartridge contains the electrophotographic photosensitive member, and at least one of charging means, developing means and cleaning means, in the form of a cartridge which is detachably mountable to the main assembly of the image forming apparatus. Furthermore, the process cartridge may contain at least the electrophotographic photosensitive member and the developing means.
In an image forming apparatus such as a copying machine, a laser beam printer or the like of an electrophotographic type, an electrophotographic photosensitive member is exposed to light modulated in accordance with image information so that an electrostatic latent image is formed thereon, and the latent image is developed with a developer (toner) by developing means. The developed image is transferred onto a recording material, such as paper from said photosensitive member.
The process cartridge may further comprise a toner accommodating portion and a residual toner container for the purpose of easy maintenance and exchange of the consumables, such as toner. In the case of a color image forming apparatus, there are provided a plurality of developing means, and the degree of wear of the developing means may be different. The degree of wear of the photosensitive drum and the developing means may be different. In view of them, some parts may be formed into a smaller cartridge, for example, the developing cartridge for each color, the cleaning means and the photosensitive drum may be formed into a cartridge (photosensitive member cartridge).
It is known that storing means (memory) may be carried on the cartridge, and the information peculiar to the cartridge is managed. In U.S. Pat. No. 5,272,503, the degree of use of the cartridge is stored in the memory, in accordance with which various process conditions are controlled. For example, the charging current value and/or the exposure amount is adjusted. The same control is carried out if the degree of use is the same, despite the fact that the cartridge is different.
Japanese Laid-open Patent Application Hei 9-120198 discloses that a driving parameter of image forming means (the voltage applied to the charger or the current applied to the exposure means) is switched in accordance with the degree of use of the cartridge, so that the image quality is maintained constant from the start of use to the end of the cartridge.
However, even if the cartridges are manufactured under the same design, and the driving parameter of the image forming means is controlled, the image quality is not uniform if the lots of manufacture are different and/or if the use timing is different.
Accordingly, it is a principal object of the present invention to provide an image forming apparatus and a cartridge detachably mountable to the main assembly of the image forming apparatus, wherein the image quality is stabilized despite a degree of usage of the cartridge.
It is another object of the present invention to provide an image forming apparatus and a cartridge detachably mountable to the main assembly of the image forming apparatus, wherein the image quality is stabilized despite the difference of manufacturing lots.
According to an aspect of the present invention, there is provided an image forming apparatus comprising image forming means for forming an image on a recording material, wherein at least a part of the image forming means is in the form of a unit which is detachably mountable to a main assembly of the apparatus, the apparatus comprising a memory, wherein the memory is mounted to the unit, wherein the memory stores information relating to the timing at which a driving parameter of the image forming means is changed.
According to another aspect of the present invention, there is provided an image forming apparatus comprising forming means for forming an image on a recording material, wherein at least a part of the image forming means is formed into a unit which is detachably mountable to a main assembly of the apparatus; memory, wherein the memory is provided in the unit, wherein the memory stores information for setting a driving parameter for the image forming means upon start of use of the unit.
According to a further aspect of the present invention, there is provided a unit detachably mountable to an image forming apparatus including image forming means for forming an image on a recording material, the unit comprising at least part of the image forming means; a memory; wherein the memory stores information relating to timing for changing a driving parameter of the image forming means.